U.S. patent number 5,700,617 [Application Number 08/727,219] was granted by the patent office on 1997-12-23 for toner for developing electrostatic images and charge-controlling agent.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Ryoichi Fujita, Tetsuya Ida, Wakashi Iida, Makoto Kanbayashi, Kenji Okado, Tsuyoshi Takiguchi, Masaaki Taya.
United States Patent |
5,700,617 |
Takiguchi , et al. |
December 23, 1997 |
**Please see images for:
( Certificate of Correction ) ** |
Toner for developing electrostatic images and charge-controlling
agent
Abstract
A toner for developing an electrostatic image is formed from
toner particles containing a binder resin, a colorant, and a
charge-controlling agent. The charge-controlling agent comprises an
aromatic oxycarboxylic acid, a metal compound of the aromatic
oxycarboxylic acid, and an inorganic compound formed from an
inorganic anion and an inorganic cation. The aromatic oxycarboxylic
acid, the metal compound of the aromatic carboxylic acid and the
inorganic anion are contained in proportions of A (wt. %), B (wt.
%) and C (ppm), respectively, satisfying the following conditions:
1/99.ltoreq.A/B.ltoreq.20/80, and 10.sup.2 .ltoreq.C. Because of
the inclusion of an inorganic compound providing a sufficient
amount of inorganic anion, the charge-controlling agent shows a
stable charge-controlling characteristic, and the resultant toner
exhibits a stable developing performance and transferability in
continuous image formation in various environmental conditions.
Inventors: |
Takiguchi; Tsuyoshi (Kawasaki,
JP), Okado; Kenji (Yokohama, JP), Taya;
Masaaki (Kawasaki, JP), Fujita; Ryoichi (Tokyo,
JP), Kanbayashi; Makoto (Kawasaki, JP),
Iida; Wakashi (Higashikurume, JP), Ida; Tetsuya
(Kawasaki, JP) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
|
Family
ID: |
17740452 |
Appl.
No.: |
08/727,219 |
Filed: |
October 8, 1996 |
Foreign Application Priority Data
|
|
|
|
|
Oct 12, 1995 [JP] |
|
|
7-289228 |
|
Current U.S.
Class: |
430/108.3;
252/500; 430/108.4 |
Current CPC
Class: |
G03G
9/09783 (20130101); G03G 9/09708 (20130101); G03G
9/09733 (20130101) |
Current International
Class: |
G03G
9/097 (20060101); G03G 009/097 (); H01B 001/00 ();
H01B 001/06 () |
Field of
Search: |
;430/110
;252/500,518 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0488743 |
|
Jun 1992 |
|
EP |
|
0490370 |
|
Jun 1992 |
|
EP |
|
0531146 |
|
Sep 1992 |
|
EP |
|
42-23910 |
|
Nov 1967 |
|
JP |
|
43-24748 |
|
Oct 1968 |
|
JP |
|
55-42752 |
|
Nov 1980 |
|
JP |
|
63-2074 |
|
Jan 1988 |
|
JP |
|
63-33755 |
|
Feb 1988 |
|
JP |
|
63-208865 |
|
Aug 1988 |
|
JP |
|
63-237065 |
|
Oct 1988 |
|
JP |
|
64-10261 |
|
Jan 1989 |
|
JP |
|
4-83262 |
|
Mar 1992 |
|
JP |
|
4-347863 |
|
Dec 1992 |
|
JP |
|
Other References
Patent Abstracts of Japan, vol. 7, No. 192 (P-218) (-1337) Aug.
1983 for JP 58-91462..
|
Primary Examiner: Martin; Roland
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper &
Scinto
Claims
What is claimed is:
1. A toner for developing an electrostatic image, comprising toner
particles containing a binder resin, a colorant, and a
charge-controlling agent;
wherein the charge-controlling agent comprises an aromatic
oxycarboxylic acid, a metal compound of the aromatic oxycarboxylic
acid, and an inorganic compound formed from an inorganic anion and
an inorganic cation, and
the aromatic oxycarboxylic acid, the metal compound of the aromatic
carboxylic acid and the inorganic anion are contained in
proportions of A (wt. B (wt. %) and C (ppm), respectively,
satisfying the following conditions:
and
2. The toner according to claim 1, wherein A (wt. %) and B (wt. %)
satisfy the following condition:
3. The toner according to claim 1, wherein A (wt. %) and B (wt. %)
satisfy the following condition:
4. The toner according to claim 1, wherein the aromatic
oxycarboxylic acid, the metal compound of the aromatic
oxycarboxylic acid, the inorganic anion and the inorganic cation
are contained in proportions of A (wt. %), B (wt. %), C (ppm) and D
(ppm), respectively, satisfying the following conditions:
and
5. The toner according to claim 4, wherein C (ppm) is at least
2.times.10.sup.2 (ppm).
6. The toner according to claim 4, wherein A (wt. %), B (wt. %) and
C (ppm) satisfy the following conditions:
and
7. The toner according to claim 4, wherein A (wt. %), B (wt. %) and
C (ppm) satisfy the following conditions:
and
8. The toner according to claim 1, wherein the inorganic cation of
the inorganic compound is an alkali metal ion.
9. The toner according to claim 1, wherein the inorganic anion of
the inorganic compound is a sulfate ion or a halide ion.
10. The toner according to claim 1, wherein the aromatic
oxycarboxylic acid is a substituted aromatic hydroxycarboxylic acid
or a substituted aromatic alkoxycarboxylic acid.
11. The toner according to claim 10, wherein the aromatic
oxycarboxylic acid has an alkyl group substituent.
12. The toner according to claim 1, wherein the aromatic
oxycarboxylic acid is a compound selected from the group consisting
of salicylic acid, alkylsalicylic acid, dialkylsalicylic acid,
hydroxynaphthoic acid, and alkylhydroxynaphthoic acid.
13. The toner according to claim 1, wherein the aromatic
oxycarboxylic acid is 3,5-di-tert-butylsalicylic acid or
5-tert-octylsalicylic acid.
14. The toner according to claim 1, wherein the metal compound of
the aromatic oxycarboxylic acid comprises a metal having a valence
of at least 2.
15. The toner according to claim 1, wherein the charge-controlling
agent comprises di-tert-butylsalicylic acid, di-tert-butylsalicylic
acid aluminum compound, sodium ion and sulfate ion.
16. The toner according to claim 1, wherein the charge-controlling
agent comprises di-tert-butylsalicylic acid, di-tert-butylsalicylic
acid chromium compound, sodium ion and sulfate ion.
17. The toner according to claim 1, wherein the charge-controlling
agent comprises di-tert-butylsalicylic acid, di-tert-butylsalicylic
acid zinc compound, sodium ion and sulfate ion.
18. The toner according to claim 1, wherein the charge-controlling
agent comprises 5-tert-octylsalicylic acid, 5-tert-octylsalicylic
acid aluminum compound, sodium ion and sulfate ion.
19. The toner according to claim 1, wherein the binder resin
comprises a polymer selected from the group consisting of styrene
copolymer, polyester resin and epoxy resin.
20. The toner according to claim 1, wherein the charge-controlling
agent is contained in an amount of 0.5-15 wt. parts per 100 wt.
parts of the binder resin.
21. The toner according to claim 1, wherein the charge-controlling
agent is contained in an amount of 1-10 wt. parts per 100 wt. parts
of the binder resin.
22. The toner according to claim 1, wherein the toner particles are
negatively chargeable.
23. The toner according to claim 1, wherein the charge-controlling
agent has a volume resistivity of at most 9.5.times.10.sup.8
ohm.cm.
24. A charge-controlling agent, comprising an aromatic
oxycarboxylic acid, a metal compound of the aromatic oxycarboxylic
acid, and an inorganic compound formed from an inorganic anion and
an inorganic cation,
wherein the aromatic oxycarboxylic acid, the metal compound of the
aromatic carboxylic acid and the inorganic anion are contained in
proportions of A (wt. B (wt. %) and C (ppm), respectively,
satisfying the following conditions:
and
25.
25. The charge-controlling agent according to claim 24, wherein A
(wt. %) and B (wt. %) satisfying the following condition:
26. The charge-controlling agent according to claim 24, wherein A
(wt. %) and B (wt. %) satisfying the following condition:
27. The charge-controlling agent according to claim 24, wherein the
aromatic oxycarboxylic acid, the metal compound of the aromatic
oxycarboxylic acid, the inorganic anion and the inorganic cation
are contained in proportions of A (wt. %), B (wt. %), C (ppm) and D
(ppm), respectively, satisfying the following conditions:
and
28. The charge-controlling agent according to claim 27, wherein C
(ppm) is at least 2.times.10.sup.2 (ppm).
29. The charge-controlling agent according to claim 27, wherein A
(wt. %), B (wt. %) and C (ppm) satisfying the following
conditions:
and
30. The charge-controlling agent according to claim 27, wherein A
(wt. %), B (wt. %) and C (ppm) satisfying the following
conditions:
and
31. The charge-controlling agent according to claim 24, wherein the
inorganic cation of the inorganic compound is an alkali metal
ion.
32. The charge-controlling agent according to claim 24, wherein the
inorganic anion of the inorganic compound is a sulfate ion or a
halide ion.
33. The charge-controlling agent according to claim 24, wherein the
aromatic oxycarboxylic acid is a substituted aromatic
hydroxycarboxylic acid or a substituted aromatic alkoxycarboxylic
acid.
34. The charge-controlling agent according to claim 33, wherein the
aromatic oxycarboxylic acid has an alkyl group substituent.
35. The charge-controlling agent according to claim 24, wherein the
aromatic oxycarboxylic acid is a compound selected from the group
consisting of salicylic acid, alkylsalicylic acid, dialkylsalicylic
acid, hydroxynaphthoic acid, and alkylhydroxynaphthoic acid.
36. The charge-controlling agent according to claim 24, wherein the
aromatic oxycarboxylic acid is 3,5-di-tert-butylsalicylic acid or
5-tert-octylsalicylic acid.
37. The charge-controlling agent according to claim 24, wherein the
metal compound of the aromatic oxycarboxylic acid comprises a metal
having a valence of at least 2.
38. The charge-controlling agent according to claim 24, wherein the
charge-controlling agent comprises di-tert-butylsalicylic acid,
di-tert-butylsalicylic acid aluminum compound, sodium ion and
sulfate ion.
39. The charge-controlling agent according to claim 24, wherein the
charge-controlling agent comprises di-tert-butylsalicylic acid,
di-tert-butylsalicylic acid chromium compound, sodium ion and
sulfate ion.
40. The charge-controlling agent according to claim 24, wherein the
charge-controlling agent comprises di-tert-butylsalicylic acid,
di-tert-butylsalicylic acid zinc compound, sodium ion and sulfate
ion.
41. The charge-controlling agent according to claim 24, wherein the
charge-controlling agent comprises 5-tert-octylsalicylic acid,
5-tert-octylsalicylic acid aluminum compound, sodium ion and
sulfate ion.
42. The charge-controlling agent according to claim 24, having a
negative charge-controllability.
43. The charge-controlling agent according to claim 24, having a
volume resistivity of at most 9.5.times.10.sup.8 ohm.cm.
Description
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a toner for developing
electrostatic images in image forming methods, such as
electrophotography and electrostatic recording, and a
charge-controlling agent for such a toner.
Hitherto, various methods based on electrophotography have been
proposed, e.g., in U.S. Pat. Nos. 2,297,691; 3,666,363 (corr. to
Japanese Patent Publication (JP-B) 42-23910); and U.S. Pat. No.
4,071,361 (corr. to JP-B 43-24748).
Developing methods for developing electrostatic images include
dry-process developing methods and wet-process developing methods.
The former further includes a method using a two-component type
developer and a method using a mono-component type developer.
In the dry developing methods, there has been used a toner
comprising fine toner particles formed by dispersing a dye or a
pigment in a natural or synthetic resin. The toner particles may
comprise finely pulverized particles on the order of 1-30 .mu.m
comprising a colorant or a magnetic material dispersed in a binder
resin, such as a styrene copolymer. A magnetic toner may contain
magnetic particles of, e.g., magnetite. In a two-component type
developer, a toner may ordinarily be blended with carrier particles
of, e.g., iron powder or magnetic ferrite particles.
A toner is caused to have a positive or negative charge depending
on the polarity of an electrostatic image to be developed
therewith.
A toner can be charged by utilizing a triboelectric chargeability
of a resin as a toner component, but the toner chargeability in
this case is generally low, thus being liable to provide unclear
developed images accompanied with fog. In order to provide a
desired triboelectric chargeability to a toner, it has been
frequently practiced to add to the toner a dye and/or a pigment,
and further a charge-controlling agent, for imparting a
chargeability.
The charge-controlling agents include a positive charge-controlling
agent, examples of which may include: nigrosine dyes, azine dyes,
copper phthalocyanine pigments, quaternary ammonium salts, and
polymers having a quaternary ammonium salt as a side chain group;
and also a negative charge-controlling agent, examples of which may
include: metal complex salts of monoazo dyes; metal complexes or
metal salts of salicylic acid, naphthoic acid, dicarboxylic acids
and derivatives of these; and resins having an acidic group.
Among the above, charge-controlling agents, which are colorless,
white or pale-colored, are useful for constituting color
toners.
Examples of such charge-controlling agents having also a negative
chargeability may include those obtained from aromatic carboxylic
acid derivatives. Thus, proposals have been made regarding the use
of toner containing an aromatic carboxylic acid derivative or a
metal compound of aromatic carboxylic acid derivative. For example,
U.S. Pat. No. 4,206,064 (corr. to JP-B 55-42752) has proposed
salicylic acid metal compounds and alkylsalicylic acid metal
compounds. Japanese Laid-Open Patent Application (JP-A) 63-2074,
JP-A 63-33755 and JP-A 4-83262 have proposed salicylic acid-based
zinc compounds. JP-A 63-208865, JP-A 63-237065 and JP-A 64-10261
have proposed salicylic acid-based aluminum compounds. JP-A
4-347863 has proposed a toner containing a mixture of a polycyclic
aromatic hydroxycarboxylic acid and an aromatic hydroxycarboxylic
acid metal compound. U.S. Pat. No. 5,346,795 has proposed a toner
containing a salicylic acid-based compound and a salicylic
acid-based aluminum compound in a weight ratio of 1/4-4/1 (i.e.,
20:80 to 80:20).
However, the toners disclosed in these references do not contain an
inorganic compound formed of an inorganic anion and an inorganic
cation in addition to the aromatic oxycarboxylic acid, so that it
has been difficult to provide a high successive image forming
performance, a high developing performance and a high
transferability, in combination, by using these toners.
A non-magnetic color toner is frequently blended with magnetic
carrier particles to be used as a two-component type developer. In
this instance, the developer is generally supplied to a
developer-carrying member surface, carried thereon under the action
of a magnetic force exerted by a magnet contained inside the
developer-carrying member surface and then conveyed to an
electrostatic image-bearing member surface to develop an
electrostatic image on the electrostatic image-bearing member
surface with the toner in the developer.
A resultant toner image is transferred onto a transfer-receiving
material for recording (generally, paper) to be fixed thereon under
application of energy, such as heat and/or pressure. During the
developing and transfer processes, the toner carried
electrostatically is moved from the carrier particles to the
electrostatic image-bearing member or from the electrostatic
image-bearing member to the transfer-receiving material under the
action of an electrostatic force in opposite directions.
In this way, the toner movement during the developing and transfer
is initiated by peeling caused by overcoming a constraint of
Coulomb's force exerted by the carrier particles or the
electrostatic image-bearing member. At the time of peeling, it is
preferred that the charge of the toner particle surfaces is
re-combined to be extinguished to some extent with the charge of
opposite polarity of the carrier particles or the electrostatic
image-bearing member surface, thus reducing the Coulomb's
attraction force in view of the energy for peeling.
More specifically, by promoting the recombination of charges of
opposite polarities, the developing and transferring performances
of the toner can be remarkably improved to result in images with
high image density and image quality of highlight portions.
However, easy recombination of opposite polarity charges can lead
to a lowering in triboelectric charge during the blending of the
toner and the carrier, so that it is liable to cause the occurrence
of fog and toner scattering during a continuous image formation
operation.
In view of the above-mentioned problems, it has been desired to
provide a charge-controlling agent capable of providing a toner
with an improved flowability, suppressed lowering in charging speed
in a low-humidity environment and chargeability in a high-humidity
environment, and also a reduction in peeling energy due to
recombination of charges.
SUMMARY OF THE INVENTION
A principal object of the present invention is to provide a
charge-controlling agent and a toner for developing electrostatic
images capable of solving the above-mentioned problems.
A more specific object of the present invention is to provide a
charge-controlling agent capable of providing a toner showing a
high charging speed in a low-humidity environment and retaining a
high triboelectric chargeability in a high-humidity environment,
and also a toner for developing electrostatic images causing little
fog and showing good continuous image forming characteristic by
using the charge-controlling agent.
Another object of the present invention is to provide a toner for
developing electrostatic images showing a high powder flowability
and capable of providing high-quality images.
Another object of the present invention is to provide a
charge-controlling agent capable of providing a toner which is
easily peelable from the carrier or the electrostatic image-bearing
member while retaining a high triboelectric charge, and also for
developing electrostatic images capable of realizing high image
density and high transferability by containing such a
charge-controlling agent.
According to the present invention, there is provided a toner for
developing an electrostatic image, comprising toner particles
containing a binder resin, a colorant, and a charge-controlling
agent;
wherein the charge-controlling agent comprises an aromatic
oxycarboxylic acid, a metal compound of the aromatic oxycarboxylic
acid, and an inorganic compound formed from an inorganic anion and
an inorganic cation, and
the aromatic oxycarboxylic acid, the metal compound of the aromatic
carboxylic acid and the inorganic anion are contained in
proportions of A (wt. %), B (wt. %) and C (ppm), respectively,
satisfying the following conditions:
and
According to another aspect of the present invention, there is
provided a charge-controlling agent, comprising an aromatic
oxycarboxylic acid, a metal compound of the aromatic oxycarboxylic
acid, and an inorganic compound formed from an inorganic anion and
an inorganic cation,
wherein the aromatic oxycarboxylic acid, the metal compound of the
aromatic carboxylic acid and the inorganic anion are contained in
proportions of A (wt. %), B (wt. %) and C (ppm), respectively,
satisfying the following conditions:
and
These and other objects, features and advantages of the present
invention will become more apparent upon a consideration of the
following description of the preferred embodiments of the present
invention taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustration of an apparatus for measuring the volume
resistivity of a powdery material, such as a charge-controlling
agent.
FIG. 2 is an illustration of an apparatus for measuring the
triboelectric chargeability of a toner.
DETAILED DESCRIPTION OF THE INVENTION
Herein, a metal compound of an aromatic oxycarboxylic acid refers
to a compound having a bond between an oxygen atom of carboxyl
group in the aromatic oxycarboxylic acid and a metal. The bond
refers to a chemical bond, such as an ionic bond, a covalent bond
or a coordinate bond. It is possible that the aromatic
oxycarboxylic acid has a further bond with the metal at a part
other than the carboxyl group.
A toner containing a metal compound of an organic acid as a
charge-controlling agent may have a relatively high triboelectric
chargeability in some cases but is generally liable to show a
lowering in triboelectric chargeability in a high-humidity
environment. On the other hand, in a low-humidity environment, the
toner is liable to show a lower charging speed.
This may be attributable to moisture adsorption and desorption near
the metal atom such that the moisture adsorption to the metal
compound is increased to result in a lower triboelectric charge in
a high-humidity environment but is decreased to provide a higher
resistivity and a lower charging speed in a low-humidity
environment.
According to our study, it has been found possible to suppress the
lowering in triboelectric chargeability in a high-humidity
environment and the lowering in charging speed in a low-humidity
environment by incorporating a specific proportion of an aromatic
oxycarboxylic acid in addition to the metal compound of the
aromatic oxycarboxylic acid.
The mechanism of the improvement has not been fully clarified as
yet, but the specific proportion of the aromatic oxycarboxylic acid
may be assumed to block or control the moisture adsorption onto the
metal compound.
The addition effect of the aromatic oxycarboxylic acid is however
little unless the aromatic oxycarboxylic acid is identical in
species to the aromatic hydroxycarboxylic acid constituting the
metal compound. This may be attributable to the stability of the
metal compound associated with the acid strength and symmetry of
the aromatic oxycarboxylic acid.
Herein, the term "aromatic oxycarboxylic acid" is used to refer to
a substituted or unsubstituted aromatic hydroxycarboxylic acid and
a substituted or unsubstituted aromatic alkoxycarboxylic acid
(preferably having 1-6 carbon atoms in the alkoxy group). Such an
aromatic oxycarboxylic acid can provide a higher chargeability to
the resultant charge-controlling agent presumably because of an
effect of a substituent bonded to an aromatic ring through the
oxygen atom for lowering the negative charge density on the oxygen
atom in the carboxyl group.
The aromatic oxycarboxylic acid may be substituted with one or more
groups. Preferred examples of such substituted aromatic
oxycarboxylic acid may include monoalkyl- or dialkyl-aromatic
oxycarboxylic acids having preferably 1-12 carbon atoms in each
alkyl group because of a high chargeability even in a high-humidity
environment. This may be attributable to a small negative charge
density of carboxyl group oxygen due to a resonance structure of
the monoalkyl- or dialkyl-aromatic oxycarboxylic acid, a
three-dimensionally large structure of the co-present monoalkyl- or
dialkyl-substituted aromatic oxycarboxylic acid functioning to
block water molecules.
Preferred examples of the aromatic hydroxycarboxylic acid may
include salicylic acid, and hydroxynaphthoic acid each preferably
having one or two alkyl groups. Preferred species of the aromatic
hydroxycarboxylic acid may include salicylic acid, alkylsalicylic
acid, dialkylsalicylic acid, hydroxynaphthoic acid and
alkylhydroxynaphthoic acid. 3,5-Di-tert-butylsalicylic acid and
5-tert-octylsalicylic acid are particularly preferred as the
aromatic hydroxycarboxylic acid. Preferred examples of the aromatic
alkoxycarboxylic acid may be obtained by substituting an alkoxy
group for the hydroxy group in the above compounds.
The valence and ionic radius of metal in the metal compound is
correlated with the strength of bond with the aromatic
oxycarbolxylic acid, and a higher metal valence and a smaller ionic
radius lead to a stronger bond with the aromatic oxycarboxylic
acid, thus providing a metal compound of which the bond is less
liable to be broken during production or long use of the toner and
which is more stably fixed in the toner particles.
According to our study, the metal constituting the metal compound
may preferably have a valence of two or more and an ionic radius of
at most 0.8 .ANG. (with reference to values listed in Table 15.23
at page 718 of "Kagaku Binran (Chemical Handbook) Revised Third
Edition" edited by the Chemical Society of Japan). Preferred
examples of the metal include aluminum, chromium and zinc, among
which aluminum is particularly preferred.
The charge-controlling agent may preferably contain the aromatic
oxycarboxylic acid and the aromatic oxycarboxylic acid metal
compound in amounts of A (wt. %) and B (wt. %) satisfying:
more preferably
further preferably
In case of A/B<1/99, the amount of the aromatic oxycarboxylic
acid blocking the metal compound from moisture is scarce, so that
the chargeability in a high-humidity environment is liable to be
lowered. On the other hand, in case of 20/80<A/B, the metal
compound is completely covered with the aromatic oxycarboxylic
acid, so that the charging speed in a low-humidity environment is
liable to be lowered and toner scattering is liable to be caused to
fail in keeping high image qualities during a long period of
use.
Further, excessive blockage of the metal compound functioning as a
charging site with the aromatic oxycarboxylic acid hinders the
recombination of charges at the time of peeling, thus resulting in
lower developing performance and transferability of the toner, as
may be presumed from increases in contact resistivity between the
metal compound and the carrier or the electrostatic image-bearing
member.
As a result of further study, based on a concept of functional
separation that the chargeability is controlled by electron
mobility and the re-combination of charges is controlled by ionic
mobility, we have arrived at the use of a charge-controlling agent
containing an inorganic compound providing inorganic anions and
inorganic cations in addition to the aromatic oxycarbolxylic acid
and the aromatic oxycarboxylic acid metal compound in a toner. As a
result, it has become possible to realize remarkable improvements
in developing performance and transferability of the toner while
maintaining the chargeability of the toner in both low-humidity and
high-humidity environments.
In case where the charge recombination is effected ionically, it is
generally considered that ions of the same polarity as the toner
charge are caused to move from inside to outside the toner
particles, so that anions contained in the anionically chargeable
charge-controlling agent of the present invention may move from
inside to outside the toner particles. As a result of our study, in
case where the anions are those of an organic compound, the
improvement in developing performance or transferability has not
been substantially attained.
This may be presumably attributable to such a mechanism that
organic anions, unlike inorganic anions, form bonds like conjugated
ones showing only a small polarization and provide ion pairs close
as a whole to neutrality, so that only a weak electrostatic
attraction force is applied from positive charges on the carrier
particles or the electrostatic image-bearing member surface, and
the movement of anions cannot be readily caused. The anions may
preferably be sulfate ions or halogen ions.
On the other hand, it has been also found that the improvement in
developing performance or transferability is not substantially
attained if cations of the inorganic compound contained in the
charge-controlling agent are organic cations. This again may be
attributable to a mechanism that organic cations provide ion pairs
showing only a weak polarization like the use of organic anions so
that the movement of anions cannot be readily caused.
The cations of the inorganic compound contained in the
charge-controlling agent of the present invention may preferably
have a fewer valence and a smaller ionic radius. This may be
presumably because a smaller valence of cation provides a weaker
bond with anion so that the movement of an anion alone at the time
of development or transfer is less hindered thereby, and a smaller
radius of ion becomes a harden ion to provide a larger polarization
between the anion and the cation, thus causing a stronger
electrostatic attraction force exerted by the positive charge on
the carrier particles and the electrostatic image-bearing member
surface, whereby the movement of anions from the inside to the
outside of the toner particles is promoted to facilitate the
recombination of charges.
According to our study, it has been found that alkali metal ions
are particularly preferred as the inorganic cations. This is
presumably because the alkali metal ions best satisfy the
above-mentioned preferred properties of the cations.
The anions and cations of the inorganic compound may preferably be
contained in C (ppm) and D (ppm) on a weight basis in the
charge-controlling agent according to the present invention
satisfying: 10.sup.2 .ltoreq.C, more preferably 2.times.10.sup.2
.ltoreq.C, and 3.times.10.sup.2 .ltoreq.C+D.
If C.gtoreq.10.sup.2 the recombination of charges can be smoothly
proceeded to provide improved developing performance and
transferability. If C+D.gtoreq.3.times.10.sup.2, a sufficient
degree of charge recombination is caused to provide an improved
charging speed in a low-humidity environment, effective prevention
of fog and toner scattering and an improved continuous image
formation performance of the toner. The upper limits of C and D are
not so strict. However, it is preferred to satisfy 2.times.10.sup.2
.ltoreq.C.ltoreq.7.times.10.sup.3, more preferably 3.times.10.sup.3
.ltoreq.C.ltoreq.6.times.10.sup.3, and 1.times.10.sup.2
.ltoreq.D.ltoreq.4.times.10.sup.4, more preferably 2.times.10.sup.2
.ltoreq.D.ltoreq.3.times.10.sup.4.
According to our study, it has been also found the resistivity of
the charge-controlling agent also remarkably affect the developing
performance and transferability of the resultant toner. The
resistivity of the charge-controlling agent directly indicates the
mobility of ions contained in the charge-controlling agent, and a
smaller resistivity is assumed to promote the charge recombination.
In fact, according to our study, a charge-controlling agent having
a volume resistivity of at most 9.5.times.10.sup.8 ohm.cm (as
measured according a method described hereinafter) provided good
results in both developing performance and transferability. The
volume resistivity of the charge-controlling agent may be varied by
appropriate control of species and amounts of the inorganic anions
and cations constituting the inorganic compound so as to provide a
volume of at most 9.5.times.10.sup.8 ohm.cm. The volume resistivity
may more preferably be in the range of 1.times.10.sup.6
-9.4.times.10.sup.8 ohm.cm.
The charge-controlling agent may preferably be added in an amount
of 0.5-15 wt. parts per 100 wt. parts of the binder resin
constituting the toner. Below 0.5 wt. part, the above-mentioned
effects can be exhibited only in a low degree. On the other hand,
in excess of 15 wt. parts, the deterioration of carrier performance
due to deposition of the toner (spent toner accumulation) is liable
to occur, thus leading to occurrence of fog and toner scattering
due to a lowering in chargeability during continuous image
formation. An amount of 1-10 wt. parts is further preferred.
The charge-controlling agent according to the present invention may
be produced through a diversity of methods, such as a method of
adding an aromatic oxycarboxylic acid and an anion and a cation for
constituting the inorganic compound to a metal compound of the
aromatic oxycarboxylic acid after preparation of the metal compound
through a known process, or a one-step method or process of
effecting appropriate pH control, etc., during a process for
synthesis of the aromatic oxycarboxylic acid metal compound.
The toner according to the present invention can contain a known
charge-controlling agent in addition to the charge-controlling
agent of the present invention. The charge-controlling agent may be
internally or externally added to toner particles, but the internal
addition within toner particles is preferred.
The binder resin for the toner of the present invention may for
example comprise: homopolymers of styrene and derivatives thereof,
such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene;
styrene copolymers such as styrene-p-chlorostyrene copolymer,
styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer,
styrene-acrylate copolymer, styrene-methacrylate copolymer,
styrene-methyl .alpha.-chloromethacrylate copolymer,
styrene-acrylonitrile copolymer, styrene-vinyl methyl ether
copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl
methyl ketone copolymer, styrene-butadiene copolymer,
styrene-isoprene copolymer and styrene-acrylonitrile-indene
copolymer; polyvinyl chloride, phenolic resin, natural
resin-modified phenolic resin, natural resin-modified maleic acid
resin, acrylresin, acrylic resin, methacrylic resin, polyvinyl
acetate, silicone resin, polyester resin, polyurethane, polyamide
resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral,
terpene resin, chmarone-indene resin and petroleum resin. Among
these, styrene copolymer, polyester resin and epoxy resin are
preferred in order to provide a negatively chargeable toner.
A crosslinked styrene copolymer and a crosslinked polyester resin
are also preferred binder resins.
Examples of the comonomer constituting such a styrene copolymer
together with styrene monomer may include other vinyl monomers
inclusive of: monocarboxylic acids having a double bond and
derivative thereof, such as acrylic acid, methyl acrylate, ethyl
acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate,
2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl
methacrylate, ethyl methacrylate, butyl methacrylate, octyl
methacrylate, acrylonitrile, methacrylonitrile, and acrylamide;
dicarboxylic acids having a double bond and derivatives thereof,
such as maleic acid, butyl maleate, methyl maleate and dimethyl
maleate; vinyl esters, such as vinyl chloride, vinyl acetate, and
vinyl benzoate; ethylenic olefins, such as ethylene, propylene and
butylene; vinyl ketones, such as vinyl methyl ketone and vinyl
hexyl ketone; and vinyl ethers, such as vinyl methyl ether, vinyl
ethyl ether, and vinyl isobutyl ether. These vinyl monomers may be
used alone or in mixture of two or more species in combination with
the styrene monomer.
The crosslinking agent may principally be a compound having two or
more double bonds susceptible of polymerization, examples of which
may include: aromatic divinyl compounds, such as divinylbenzene,
and divinylnaphthalene; carboxylic acid esters having two double
bonds, such as ethylene glycol diacrylate, ethylene glycol
dimethacrylate and 1,3-butanediol dimethacrylate; divinyl
compounds, such as divinylaniline, divinyl ether, divinyl sulfide
and divinylsulfone; and compounds having three or more vinyl
groups. These may be used singly or in mixture.
A binder resin principally comprising a styrene-acryl copolymer
(i.e., a copolymer of styrene with an acrylic monomer, such as
(meth)acrylate or (meth)acrylic acid) may preferably be one
including a THF (tetrahydrofuran)-soluble content providing a
molecular weight distribution by GPC (gel permeation
chromatography) showing at least one peak (preferably a main peak)
in a molecular weight region of 3.times.10.sup.3 -5.times.10.sup.4
and at least one peak in a molecular weight region of at least
10.sup.5 and containing 50-90 wt. % of a component having a
molecular weight of at most 10.sup.5.
A binder resin principally comprising a polyester resin may
preferably have such a molecular weight distribution that it shows
at least one peak in a molecular weight region of 3.times.10.sup.3
-5.times.10.sup.4 and contains 60-100 wt. % of a component having a
molecular weight of at most 10.sup.5. It is further preferred to
have at least one peak within a molecular weight region of
5.times.10.sup.3 -2.times.10.sup.4.
A polyester resin is excellent in fixability and is suitable for
provide a color toner. It is particularly preferred to use a
polyester resin obtained by subjecting a diol principally
comprising a bisphenol derivative represented by the following
formula or a substitution derivative thereof: ##STR1## (wherein R
denotes an ethylene or propylene group, x and y are independently a
positive integer of at least 1 with the proviso that the average of
x+y is in the range of 2-10); with a carboxylic acid component
comprising a carboxylic acid having two or more functional groups
(carboxylic groups), its anhydride or a lower alkyl ester thereof
(e.g., fumaric acid, maleic acid, maleic anhydride, phthalic acid,
terephthalic acid, trimellitic acid, pyromellitic acid) because of
a good chargeability characteristic.
It is possible to provide a magnetic toner by incorporating a
magnetic material as the colorant. The magnetic material may
preferably be in the form of fine powder having an average particle
size (diameter) of 0.05-0.5 .mu.m, more preferably 0.1-0.4 .mu.m.
The magnetic fine powder may preferably have a coefficient of
variation in particle size of at most 30%. The magnetic fine powder
may preferably be contained in an amount of 40-120 wt. parts per
100 wt. parts of the binder for constituting a magnetic toner.
The magnetic material may for example comprise: iron oxides, such
as magnetite, .gamma.-iron oxide, ferrite and excessive iron-type
ferrite; metals, such as iron, cobalt and nickel, and alloys of
these metals with a metal, such as aluminum, cobalt, copper, lead,
magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium,
calcium, manganese, selenium, titanium, tungsten, or vanadium; and
mixtures of the above.
The toner particles can contain wax.
The wax used in the present invention may include hydrocarbon wax,
examples of which may include: alkylene polymer obtained by radical
polymerization of alkylene under a high pressure; alkylene polymer
obtained by polymerization under a low pressure by using a Ziegler
catalyst; alkylene polymer obtained by thermal decomposition of
high-molecular weight alkylene polymer; and synthetic hyrocarbons
obtained by hydrogenating distillation residue of hydrocarbons
obtained from synthesis gas containing carbon monoxide and hydrogen
through the Arge process. It is particularly preferred to use a
hydrocarbon wax obtained by fractionating the above-mentioned
hydrocarbon waxes into a particular fraction, e.g., by the press
sweating method, the solvent method, the vacuum distillation and
fractionating crystallization, for removing a low-molecular weight
fraction or for collecting a low-molecular weight fraction.
Other types of waxes may include microcrystalline wax, carnauba
wax, sasol wax, paraffin wax and ester wax.
The wax may preferably have a number-average molecular weight (Mn)
of 500-1200 and a weight-average molecular weight (Mw) of 800-3600
when measured as equivalent to polyethylene. When the molecular
weight is below the above-mentioned range, the resultant toner is
caused to have inferior anti-blocking characteristic and developing
performance. Above the above-mentioned molecular weight range, it
becomes difficult to obtain a toner showing good fixability and
anti-offset characteristic.
The wax may preferably have an Mw/Mn ratio of at most 5.0, more
preferably at most 3.0.
The wax may effectively be contained in an amount of 0.5-10 wt.
parts per 100 wt. parts of the binder resin.
The colorants may include known chromatic and black to white
pigments. Among these, an organic pigment having a high
lipophilicity may be preferred.
Examples thereof may include: Naphthol Yellow S, Hansa Yellow G,
Permanent Yellow NCG, Permanent Orange GTR, Pyrazolone Orange,
Benzidine Orange G, Permanent Red 4R, Watching Red calcium salt,
Brilliant Carmine 38, Fast Violet B, Methyl Violet Lake,
Phthalocyanine Blue, Fast Sky Blue and Indanthrene Blue BC.
It is preferred to use pigments, e.g., of the polycondensed azo
type, insoluble azo type, quinacridone type, isoindolinone type,
perylene type, anthraquinone type and copper phthalocyanine type,
because of high light-resistance.
More specifically, magenta pigments may include: C.I. Pigment Red
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53,
54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114,
122, 123, 163, 202, 206, 207, 209, 238; C.I. Pigment Violet 19;
C.I. Vat Red 1, 2, 10, 13, 15, 23, 29, 35.
Cyan pigments may include C.I. Pigment Blue 2, 3, 15, 16, 17; C.I.
Vat Blue 6; C.I. Acid Blue 45; and copper phthalocyanine pigments
represented by the following formula (1) and having a
phthalocyanine skeleton and 1-5 phthalimide methyl groups as
substituents: ##STR2##
Yellow pigments may include; C.I. Pigment Yellow 1, 2, 3, 4, 5, 6,
7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 74, 81, 83, 93, 94,
95, 97, 98, 109, 120, 128, 138, 147, 151, 154, 166, 167, 173, 180,
181: C.I. Vat Yellow 1, 3, 20.
In the present invention, it is preferred to use a pigment in the
form of a paste as produced from a known wet pigment production
process, i.e., obtained without any drying step from a slurry
before a filtration step in the production process. In other words,
it is not preferred to use a pasty pigment obtained by wetting with
water a once-dried powdery pigment.
The content of such an organic pigment may be at most 12 wt. parts,
preferably 0.5-7 wt. parts per 100 wt. parts of the binder resin,
for a yellow toner which sensitively affect the transparency of an
OHP (overhead projector) film. In excess of 12 wt. %, the
reproducibility of green or red as a mixture color of yellow, or
the color of human skin occurring in images, can be lowered.
An organic colorant may preferably be contained in an amount of at
most 15 wt. parts, more preferably 0.1-9 wt. parts, per 100 wt.
parts of the binder resin for a magenta or a cyan color toner.
The toner particles thus prepared according to the present
invention may have a good flowability as they are, but can be
blended further with a flowability improving agent.
The flowability improving agent may comprise any substance,
preferably a powdery substance, capable of providing the toner with
increased flowability by the addition thereof. Examples thereof may
include: hydrophobic colloidal silica fine powder, colloidal silica
fine powder, hydrophobic titanium oxide fine powder, titanium oxide
fine powder, hydrophobic alumina fine powder, alumina fine powder,
and powdery mixtures of the above.
Toner particles according to the present invention may be produced
through a process wherein component materials as described above
are well-kneaded by a hot kneading means, such as hot rollers, a
kneader and an extruder, followed by mechanical pulverization and
classification of the kneaded product; a process wherein the
materials, such as the colorant and the charge-controlling agent
are dispersed in a binder resin solution, and the resultant
dispersion is dried by spraying; a polymerization toner production
process wherein the component materials are dispersed in a monomer
for providing the binder resin to provide a polymerizable mixture,
which is then emulsified or suspended in an aqueous medium and
polymerized therein to provide toner particles.
The toner according to the present invention can be blended with
carrier particles to provide a two-component type developer. In
this instance, it is possible to surface-coat the carrier particles
with various materials, particularly resin. In this case, the
species and the amount of the coating resin may be appropriately
selected depending on the required charging performance,
resistivity and surface unevenness of the carrier.
Examples of the coating resin may include: styrene-acrylate
copolymer, styrene-methacrylate copolymer, other acrylate
copolymers and methacrylate copolymers, modified or unmodified
silicone resin, fluorine-containing resin, polyamide resin, ionomer
resin, polyphenylene sulfide resin and mixtures of these
resins.
The carrier core may comprise or magnetic oxide, such as ferrite,
excessive iron-type ferrite, magnetite or .gamma.-iron oxide.
A two-component type developer may be obtained by blending the
toner according to the present invention and a carrier so as to
provide a toner concentration of 1-15 wt. %, preferably 2-13 wt. %,
in the developer so as to provide generally good results. If the
toner concentration is below 1 wt. %, the image density is liable
to be low. In excess of 15 wt. %, fog and toner scattering in an
image forming machine are liable to be caused.
Hereinbelow, some methods for measuring properties characterizing
the products of the present invention and methods for evaluation
thereof will be described.
(1) Volume resistivity
The volume resistivity of a charge-controlling agent was measured
by using a measurement cell A as shown in FIG. 1. Referring to FIG.
1, the cell A includes a lower electrode 11 and an upper electrode
12 respectively having a contact area S with a sample 17 of 2
cm.sup.2. In an environment of 23.degree. C. and 65% RH, a powdery
sample is placed between the electrodes 11 and 12 within a
cylindrical insulating resin 13 held along a guide ring 18 so as to
provide a thickness d of 1 mm under a load of 15 kg from the upper
electrode 12. In this state, an AC voltage of 5000 volts (10000 Hz)
is applied across the sample 17 from a constant voltage supply 15
disposed in parallel with a capacitor 17 to read a current passing
through the sample 17 by an ammeter 14. From the measured current,
the volume resistivity of the sample 17 is calculated in an
ordinary manner.
(2) Triboelectric charge (TC [mC/kg])
An apparatus as shown in FIG. 2 was used for measuring a
triboelectric charge of toner samples.
Referring to FIG. 2, ca. 0.5-0.9 g of a developer taken from the
surface of a sleeve in a developing device is placed in a metal
measurement vessel 22 equipped with a 50 mesh-screen 23 at its
bottom, and the vessel is covered with a metal lid 24. The total
weight (W.sub.1 g) of the measurement vessel at this time is
measured. Then, an aspirator 21 (of which the portion contacting
the vessel 22 is insulating) is operated by sucking through a
suction outlet 27 while adjusting an air control valve 26 to
provide a pressure of 250 mmAq at a vacuum gauge 25. In this state,
the aspiration is sufficiently performed, preferably about 2 min.,
to remove the toner by sucking. The potential on a potential meter
29 connected to the vessel 22 via a capacitor 28 (having a
capacitance C .mu.F) is read at V volts. The total weight (W.sub.2
g) after the aspiration is measured, and the triboelectric charge
of the toner is calculated according to the following equation:
(3) Analysis of aromatic oxycarboxylic acid and inorganic anions
and cations
The contents of an aromatic oxycarboxylic acid, an inorganic cation
and an inorganic anion in a charge-controlling agent were measured
in the following manner.
For measurement of an aromatic oxycarboxylic acid content, a
weighed amount of a charge-controlling agent is dissolved in
chloroform and, into the resultant solution, acetonitrile is added
to precipitate an aromatic oxycarboxylic acid metal compound. The
resultant liquid is subjected to filtration to be separated into a
precipitate and a filtrate. A prescribed amount of n-tridecane as
an internal standard is added to the filtrate, and the resultant
solution is subjected to gas chromatography to measure the content
of the aromatic oxycarboxylic acid in comparison with the content
of the n-tridecane.
For the measurement of inorganic cation and anion constituting an
inorganic compound in a charge-controlling agent, a weighed amount
of charge-controlling agent is dissolved or swollen with methanol,
and water is added to the methanol liquid. The resultant
methanol-water mixture liquid is boiled under heating and then
filtrated. The resultant filtrate is subjected to ICP (inductively
coupled plasma) emission electroscopy to measure the content of the
inorganic cation, and another portion of the filtrate is subjected
to ion chromatography to measure the content of the inorganic
anion.
Hereinbelow, the present invention will be described more
specifically based on Examples which however should not be
construed to limit the scope of the present invention. In the
following Examples, "part(s)" and "ppm" used to describe
compositions are all by weight unless otherwise noted
specifically.
Production Example 1 for Al Compound
Aqueous solution of 0.5 mol of NaOH and 0.4 mol of
3,5-di-tert-butylsalicylic acid were mixed and heated for
dissolution. The resultant solution was added to aqueous solution
of 0.1 mol of Al.sub.2 (SO.sub.4).sub.3, and the mixture was
stirred under heating. The liquid was then neutralized and
filtrated to recover a white precipitate, which was then washed
with water and dried to obtain 3,5-di-tert-butylsalicylic acid
aluminum compound (Al Compound 1).
The resultant Al Compound 1 was found to contain substantially no
3,5-di-tert-butylsalicylic acid, but contain 40 ppm of sodium ions
and 70 ppm of sulfate ions.
Production Example for Cr Compound
Cr Compound was prepared in a similar manner as in Production
Example 1 above except for using Cr.sub.2 (SO.sub.4).sub.3 instead
of Al.sub.2 (SO.sub.4).
The resultant Cr Compound was found to contain substantially no
free 3,5-di-tert-butylsalicylic acid but contain 30 ppm of sodium
ions and 70 ppm of sulfate ions.
Production Example for Zn Compound
Zn Compound was prepared in a similar manner as in Production
Example 1 above except for using ZnCl.sub.2 instead of Al.sub.2
(SO.sub.4).
The resultant Zn Compound was found to contain substantially no
free 3,5-di-tert-butylsalicylic acid but contain 20 ppm of sodium
ions and 46 ppm of chloride ions.
Production Example 2 for Al Compound
Al Compound 2 was prepared in a similar manner as in Production
Example 1 above except for using 5-tert-octylsalicylic acid instead
of 3,5-di-tert-butylsalicylic acid.
The resultant Al Compound 2 was found to contain substantially no
free 5-tert-ethylsalicylic acid but contain 30 ppm of sodium ions
and 70 ppm of sulfate ions.
Production Example 1 for Charge Controller Composition
Into a methanol/water (=70/30) mixture solution containing
3,5-di-tert-butylsalicylic acid and sodium sulfate (Na.sub.2
SO.sub.4) dissolved therein, Al Compound 1 was dispersed, and the
resultant dispersion was dried by spray-drying to obtain Charge
Controller Composition 1, which was found to contain 240 ppm of
sodium ions and 560 ppm of sulfate ions.
The composition of Charge Controller Composition 1 is shown in
Table 1 appearing hereinafter together with those of other Charge
Controller Compositions prepared in manners described below.
Production Examples 2-4 for Charge Controller Composition
Charge Controller Compositions 2-4 were prepared in similar manners
as in Production Example 1 except for using different amounts of
3,5-di-tert-butylsalicylic acid and sodium sulfate.
Production Example 5 for Charge Controller Composition
Charge Controller Composition 5 was prepared in a similar manner as
in Production Example 1 except for using Cr Compound instead of Al
Compound 1 together with different amounts of
3,5-di-tert-butylsalicylic acid and sodium sulfate.
Production Example 6 for Charge Controller Composition
Charge Controller Composition 6 was prepared in a similar manner as
in Production Example 1 except for using Zn Compound instead of Al
Compound 1 together with different amounts of
3,5-di-tert-butylsalicylic acid and sodium sulfate.
Production Example 7 for Charge Controller Composition
Charge Controller Composition 5 was prepared in a similar manner as
in Production Example 1 except for using Al Compound 2 and
5-tert-octylsalicylic acid instead of Al Compound 1 and
3,5-di-tert-butylsalicylic acid respectively, together with a
different amount of sodium sulfate.
Production Example 8 for Charge Controller Composition
Charge Controller Composition 8 was prepared in a similar manner as
in Production Example 1 except for using different amounts of
3,5-di-tert-butylsalicylic acid and sodium sulfate.
Production Example 9 for Charge Controller Composition
Charge Controller Composition 9 was prepared in a similar manner as
in Production Example 1 except for using potassium sulfate instead
of sodium sulfate together with a different amount of
3,5-di-tertbutylsalicylic acid.
Production Example 10 for Charge Controller Composition
Charge Controller Composition 10 was prepared in a similar manner
as in Production Example 1 except for using calcium sulfate instead
of sodium sulfate together with a different amount of
3,5-di-tert-butylsalicylic acid.
Production Example 11 for Charge Controller Composition
Charge Controller Composition 11 was prepared in a similar manner
as in Production Example 1 except for using potassium chloride
instead of sodium sulfate together with a different amount of
3,5-di-tert-butylsalicylic acid.
Production Example 12 for Charge Controller Composition
(Comparative)
Charge Controller Composition 5 was prepared in a similar manner as
in Production Example 1 except for using tetra-n-butylammonium
chloride instead of sodium sulfate.
Production Example 13 for Charge Controller Composition
(Comparative)
Charge Controller Composition 13 was prepared in a similar manner
as in Production Example 1 except for using sodium
p-toluenesulfonate instead of sodium sulfate.
Production Example 14 for Charge Controller Composition
(Comparative)
Charge Controller Composition 14 was prepared in a similar manner
as in Example 1 except for using Al Compound 1 after further
washing well with hot water to reduce the sodium and sulfate ions
and using no additional sodium sulfate.
Production Example 15 for Charge Controller Composition
(Comparative)
Charge Controller Composition 15 was prepared in a similar manner
as in Example 1 except for using Al Compound 1 after further
washing well with hot water to reduce the sodium and sulfate ions,
using no additional sodium sulfate and using a different amount of
3,5-di-tert-butylsalicylic acid.
Production Example 16 for Charge Controller Composition
(Comparative)
Charge Controller Composition 16 was prepared in a similar manner
as in Production Example 1 except for using different amounts of
3,5-di-tert-butylsalicylic acid and sodium sulfate.
Production Example 17 for Charge Controller Composition
(Comparative)
Charge Controller Composition 17 was prepared in a similar manner
as in Production Example 1 except for using Al Compound 2 instead
of Al Compound 1 together with a different amount of sodium
sulfate.
Production Example 18 for Charge Controller CompositiOn
(Comparative)
Charge Controller Composition 18 was prepared in a similar manner
as in Production Example 1 except for using 5-tert-octylsalicylic
acid instead of 3,5-di-tert-butylsalicylic acid together with a
different amount of sodium sulfate.
TABLE 1
__________________________________________________________________________
Charge Metal Oxycarboxylic* Cation Anion V.R.*.sup.4 controller
component* acid A (wt. %)/B (wt. %) (D) (C) (ohm .multidot. cm)
__________________________________________________________________________
1 DTBSA.Al DTBSA 6.4/93.6 Na.sup.+, 240 ppm SO.sub.4.sup.2-, 560
ppm 9.2 .times. 10.sup.8 2 DTBSA.Al DTBSA 6.7/93.3 Na.sup.+, 460
ppm SO.sub.4.sup.2-, 1210 ppm 9.1 .times. 10.sup.8 3 DTBSA.Al DTBSA
7.2/92.8 Na.sup.+, 370 ppm SO.sub.4.sup.2-, 740 ppm 9.1 .times.
10.sup.8 4 DTBSA.Al DTBSA 1.1/98.9 Na.sup.+, 410 ppm
SO.sub.4.sup.2-, 820 ppm 9.1 .times. 10.sup.8 5 DTBSA.Cr DTBSA
5.9/94.1 Na.sup.+, 210 ppm SO.sub.4.sup.2-, 490 ppm 9.1 .times.
10.sup.8 6 DTBSA.Zn DTBSA 6.8/93.2 Na.sup.+, 220 ppm Cl.sup.-, 510
ppm 9.1 .times. 10.sup.8 7 5TOSA.Al 5TOSA 1.5/98.5 Na.sup.+, 230
ppm SO.sub.4.sup.2-, 530 ppm 9.1 .times. 10.sup.8 8 DTBSA.Al DTBSA
13.9/86.1 Na.sup.+, 220 ppm SO.sub.4.sup.2-, 530 ppm 9.3 .times.
10.sup.8 9 DTBSA.Al DTBSA 7.2/92.8 Na.sup.+, 40 ppm
SO.sub.4.sup.2-, 370 ppm 9.2 .times. 10.sup.8 K.sup.+, 260 ppm 10
DTBSA.Al DTBSA 7.2/92.8 Na.sup.+, 40 ppm SO.sub.4.sup.2-, 1130 ppm
9.1 .times. 10.sup.8 Ca.sup.2, 450 ppm 11 DTBSA.Al DTBSA 7.2/92.8
Na.sup.+, 40 ppm SO.sub.4.sup.2-, 60 ppm 9.0 .times. 10.sup.8
K.sup.+, 380 ppm Cl.sup.-, 350 ppm 12 DTBSA.Al DTBSA 6.4/93.6
Na.sup.+, 40 ppm SO.sub.4.sup.2-, 70 ppm 9.7 .times. 10.sup.8
(Comp.) **TBA, 480 ppm Cl.sup.-, 70 ppm 13 DTBSA.Al DTBSA 6.4/93.6
Na.sup.+, 390 ppm SO.sub.4.sup.2-, 70 ppm 9.6 .times. 10.sup.8
(Comp.) ***PTS, 2600 ppm 14 DTBSA.Al DTBSA 6.4/93.6 Na.sup.+, 30
ppm SO.sub.4.sup.2-, 60 ppm 9.8 .times. 10.sup.8 (Comp.) 15
DTBSA.Cl DTBSA 0.7/99.3 Na.sup.+, 30 ppm SO.sub.4.sup.2-, 60 ppm
9.6 .times. 10.sup.8 (Comp.) 16 DTBSA.Cl DTBSA 22.6/77.4 Na.sup.+,
110 ppm SO.sub.4.sup.2-, 240 ppm 9.4 .times. 10.sup.8 (Comp.) 17
5TOSA.Al DTBSA 1.5/98.5 Na.sup.+, 230 ppm SO.sub.3.sup.2-, 530 ppm
9.2 .times. 10.sup.8 (Comp.) 18 DTBSA.Al 5TOSA 1.5/98.5 Na.sup.+,
420 ppm SO.sub.4.sup.2-, 850 ppm 9.1 .times. 10.sup.8 (Comp.)
__________________________________________________________________________
*DTBSA: 3,5di-tert-butylsalicylic acid 5TOSA: 5tert-octylsalicylic
acid **TBA: tetran-butylammonium ion ***PTS: ptoluenesulfonate ion
*.sup.4 V.R. = volume resistivity
EXAMPLE
______________________________________ Polyester resin (AV (acid
value) = 1.2)** 100 parts Phthalocyanine pigment 4 parts Charge
Controller Composition 1 5 parts
______________________________________ ** A polyester resin
prepared by polycondensation of polyoxypropylene
(2,2)2,2-bis(4-hydroxyphenyl)propane with fumaric acid and
1,2,5hexane-tricarboxylic acid.
The above ingredients were subjected to sufficient preliminary
blending by a Henschel mixer and melt-kneaded through a twin-screw
extrusion kneader, followed by cooling, coarse crushing by a hammer
mill into ca. 1-2 mm and fine pulverization by an air jet mill. The
resultant fine pulverizate was classified to obtain cyan toner
particles having a weight-average particle size (D.sub.4) of 5.8
.mu.m.
On the other hand, 100 parts of hydrophilic alumina fine powder was
surface-treated with 20 parts of iso-C.sub.4 H.sub.9
--Si(OCH.sub.3).sub.3 to obtain hydrophobic alumina fine
powder.
10 wt. parts of the cyan toner particles and 1.5 parts of the
hydrophilic alumina fine powder were blended to prepare Cyan Toner
1.
EXAMPLES 2-11 AND COMPARATIVE EXAMPLES 1-7
Cyan Toners 2-18 were prepared respectively in the same manner as
in Example 1 except for using Charge Controller Compositions 2-18,
respectively, instead of Charge Controller Composition 1.
Image Forming Test
6 parts of Cyan Toner 1 (of Example 1 ) was blended with 94 parts
of coated ferrite carrier (average particle size (Dav.)=50 .mu.m)
coated with 1.5 wt. % of acryl-modified silicone resin to prepare a
two-component type developer.
The two-component type developer was charged in a full-color
digital copying machine ("CLC-800", available from Canon K.K.) and
used for a mono color-mode continuous image formation while
replenishing the toner as necessary and by using an original having
an image area occupation ratio of 25 % under different environments
of high temperature/high humidity (30.degree. C./80 % RH) and
normal temperature/low humidity (25.degree. C./10 % RH). The
continuous image formation was performed on 10000 sheets in each of
the different environments. The results are inclusively shown in
Tables 2-1 to 2-2.
As shown in Tables 2-1 and 2-2, the developer exhibited excellent
developing performance and transferability stably in the continuous
image formation test while causing little difference in different
environments. Further, the developer was free from toner scattering
after the 10000 sheets of continuous image formation test.
The same image formation test was performed by using Cyan Toners
2-18 of Examples 2-11 and Comparative Examples 1-7.
TABLE 2-1
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30.degree. C./80% RH Initial stage After 10000 sheets TC TC Toner
I.D. Quality (nC/kg) Fog I.D. Quality (nC/kg) Fog Scatter
__________________________________________________________________________
Ex. 1 1 1.71 A -27 0.4 1.72 A -26 0.5 A 2 2 1.70 A -27 0.4 1.71 A
-26 0.5 A 3 3 1.71 A -26 0.4 1.72 A -25 0.5 A 4 4 1.69 A -26 0.4
1.71 A -25 0.6 A 5 5 1.70 A -27 0.5 1.72 A -26 0.6 A 6 6 1.75 A -25
0.8 1.78 A -23 0.9 B 7 7 1.70 A -29 0.5 1.72 A -29 0.5 A 8 8 1.71 A
-28 0.5 1.70 A -28 0.6 A 9 9 1.72 A -27 0.5 1.74 A -26 0.6 A 10 10
1.64 A -26 0.4 1.66 B -25 0.5 A 11 11 1.68 A -27 0.5 1.64 A -25 0.6
A Comp. Ex. 1 12 1.61 B -25 0.6 1.58 C -23 0.7 A 2 13 1.63 B -26
0.5 1.62 C -24 0.6 A 3 14 1.62 A -28 0.4 1.57 B -26 0.6 A 4 15 1.61
A -28 0.5 1.58 B -27 0.6 A 5 16 1.68 B -29 0.4 1.70 B -29 0.5 B 6
17 1.79 A -24 0.9 1.90 B -18 2.0 D 7 18 1.80 A -22 0.9 1.91 B -18
2.1 D
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TABLE 2-2
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25.degree. C./10% RH Initial stage After 10000 sheets TC TC Toner
I.D. Quality (nC/kg) Fog I.D. Quality (nC/kg) Fog Scatter
__________________________________________________________________________
Ex. 1 1 1.67 A -34 0.4 1.66 A -33 0.5 A 2 2 1.66 A -35 0.4 1.65 A
-34 0.5 A 3 3 1.67 A -34 0.4 1.65 A -33 0.5 A 4 4 1.68 A -33 0.5
1.66 A -34 0.6 A 5 5 1.67 A -34 0.4 1.66 A -33 0.5 A 6 6 1.64 A -28
0.6 1.60 A -29 0.9 B 7 7 1.66 A -34 0.5 1.64 A -35 0.8 A 8 8 1.70 A
-33 0.4 1.62 A -34 1.2 C 9 9 1.66 A -33 0.4 1.64 A -34 0.6 A 10 10
1.60 A -35 0.4 1.58 B -34 0.5 A 11 11 1.64 A -34 0.4 1.62 A -35 0.5
A Comp. Ex. 1 12 1.53 C -32 0.5 1.44 D -33 0.6 A 2 13 1.55 C -33
0.7 1.45 D -34 0.7 A 3 14 1.56 B -35 0.4 1.50 C -37 0.9 B 4 15 1.55
B -34 0.7 1.51 C -35 1.0 B 5 16 1.59 B -36 0.6 1.53 C -39 1.5 C 6
17 1.63 A -33 0.8 1.68 B -36 1.6 D 7 18 1.62 A -32 0.9 1.66 B -34
1.9 D
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The evaluation results shown in the above Tables 2-1 and 2-2 were
obtained according to the methods and standards described below for
the respective items except for TC (triboelectric chargeability)
for which the measurement method has been already described
hereinbefore.
I.D. (Image Density)
The image density of a solid image part (showing a gloss of 25-35
as measured by a gloss meter ("PG-3D", available from Nippon
Hasshoku Kogyo K.K.)) was measured by using a Macbeth reflection
densitometer available from Macbeth Co.
Quality (Image quality of highlight portion)
Image quality of a highlight portion of an image sample was
compared with that of a standard image sample and evaluated at four
levels.
A: excellent,
B: good,
C: fair,
D: poor.
The image density (I.D.) and the quality (image quality of
highlight portion) were evaluated as measures for the developing
performance and transferability of a toner since the former are
remarkably affected by the latter properties.
Fog
Fog (%) was evaluated as a difference in reflectance based on
reflectance values measured by using "REFLECTOMETER MODEL TC-6DS"
(available from Tokyo Denshoku K.K.) together with an accessory
amber filter for cyan toner images and calculated according to the
following equation. A smaller value represents less fog.
Scatter (Toner scattering)
The degree of toner scattering out of the developing device was
evaluated around and below the developing device within the copying
apparatus by eye observation at four level.
A: No toner scattering out of the developing device at all.
B: A recognizable amount of toner found on members around the
developing device.
C: A small amount of toner spilt from the developing device found
below the developing device.
D: A large amount of toner spilt from the developing device found
below the developing device.
* * * * *